Maintenance backlog: counting it in crew-weeks by trade, ready and total backlog, reading the trend, and keeping it honest with a review
Maintenance backlog as a measure decisions can be made on: calculating it in crew-weeks by trade, total and ready backlog, the statuses that show where work is held up, the commonly cited healthy range, what the trend says, the weekly backlog review, and why a growing backlog is usually a reliability symptom. With a drawing of a backlog trend over half a year.
Key takeaways
- The maintenance backlog is all identified work not yet done. Measured in crew-weeks, the estimated hours of open work divided by the crew's weekly hours, it says how long the crew would take to clear it.
- Report it by trade and separately for ready work. A site total of four and a half weeks can hide boilermakers at eight weeks and instrument technicians at one and a half.
- A total backlog of roughly two to six crew-weeks is commonly cited as workable, with enough ready work to fill two to three weeks of schedule. The trend matters more than the number.
- Total rising while ready work falls points at planning. Both rising points at crew capacity or reliability. Too little backlog usually means work is not being found.
- A weekly review keeps it honest: duplicates closed, stale orders cancelled with a reason, priorities and estimates checked, readiness updated.
The weekly meeting reports a backlog of 1,400 work orders. Nobody knows whether that is good or bad. Some are a few minutes of work and some are a week. Some were done months ago under a different order, and some are for a pump that was removed in the last upgrade. The number goes up and down, and nothing is decided on it.
This guide covers maintenance backlog as a measure that decisions can be made on: counting it in crew-weeks by trade, the statuses that show where work is held up, the ranges commonly cited, what the trend says, and how a backlog review keeps it honest. It follows on from maintenance planning and scheduling and the maintenance KPIs. The figures are illustrative.
Counting it in crew-weeks
A count of work orders cannot be compared with anything. Crew-weeks can. For each trade, add the estimated remaining hours of every open order, then divide by the hours that trade has in a week. The result is how many weeks the crew would take to clear the work if nothing new arrived. Do the same for the work that is ready to schedule, because that is what the scheduler can draw on.
Report it by trade. Backlog cannot be moved between trades, so a site total hides the problem. In the illustration below the site total is about four and a half crew-weeks, which looks healthy. The boilermakers are at eight, with only one week ready, and the instrument technicians are at one and a half.
| Trade | Open hours | Ready hours | Hours a week | Total, crew-weeks | Ready, crew-weeks |
|---|---|---|---|---|---|
| Mechanical | 2,280 | 912 | 456 | 5.0 | 2.0 |
| Electrical | 570 | 342 | 228 | 2.5 | 1.5 |
| Boilermaker | 1,216 | 152 | 152 | 8.0 | 1.0 |
| Instrument | 171 | 114 | 114 | 1.5 | 1.0 |
A count of work orders is a list. A backlog in crew-weeks, by trade, is a decision.
Reading the trend
A total backlog of roughly two to six crew-weeks is commonly cited as workable, with enough ready work to fill two to three weeks of the schedule. Those are rules of thumb, and a site's own trend says more than any comparison with them. Plot total and ready backlog weekly, by trade, and read them together.
In the illustration, total backlog climbs for ten weeks while ready work falls. That is work arriving faster than it can be planned. A backlog review then removes about two crew-weeks of duplicate and stale orders in a single sitting, which is common the first time a site does one. With planning caught up, ready work rises, and a contract crew for six weeks brings the total back into range.
| What the trend shows | What it means | Where to look |
|---|---|---|
| Total rising, ready flat or falling | Work is arriving faster than it is planned | Planning capacity, or planners pulled onto other work |
| Total and ready both rising | The crew cannot do the work it has ready | Crew capacity short, or a reliability problem creating corrective work |
| Total under about two weeks | Not enough work identified, or the crew is larger than the work | Inspections and rounds, notification culture, or crew size |
| Awaiting parts growing | Planned work held up by supply | Reservations raised late, lead times, or stock policy |
| Old work orders piling up | Low priority work never reaches the schedule | Stale and duplicate orders, or a priority system everyone overrides |
| Awaiting shutdown growing | More work needs the plant down than the shutdowns can take | Shutdown frequency or length, or work that could be done running |
Where work is held up
Each order in the backlog sits in one status, and the hours in each status show where work is waiting. Most CMMS products hold these as user or system statuses on the work order. They only help if they are kept current, which is part of the planner's daily routine rather than a separate exercise.
| Status | What it means | Who moves it on |
|---|---|---|
| Awaiting screening | Raised, not yet checked, prioritised or approved | Supervisor or planner, daily |
| Awaiting planning | Approved, no job pack yet | Planner |
| Awaiting parts | Planned, parts on order or not yet in the store | Planner and supply |
| Awaiting shutdown | Can only be done with the plant down, held for the next suitable stop | Shutdown planner |
| Ready to schedule | Job pack, parts, permits and access all in place | Scheduler |
| Scheduled | In the frozen weekly schedule | Supervisor |
The backlog review
A backlog that is never reviewed fills with orders that will never be done. They distort the measure and bury the work that matters. A weekly review by the planner and supervisor, with a deeper review of old orders once a quarter, keeps it honest. Cancelling is fine, as long as each cancellation carries a reason and someone has looked at it. Deleting old orders in bulk to make the number look better removes the history the equipment maintenance log depends on.
| Step | What it catches | How |
|---|---|---|
| Close duplicates | The same defect raised more than once | Merge into one order and keep the history |
| Cancel what is no longer needed | Equipment changed, removed, or the defect fixed under another order | Cancel with a reason recorded, never in bulk without looking |
| Confirm the priority | Priority set by a rule from risk, not by who raised it | Re-rank old orders against today's criticality |
| Check the estimate | Orders with no hours cannot be counted | Add a rough estimate so the order counts in crew-weeks |
| Update the status | Readiness as it is today | Parts arrived, permits known, shutdown identified |
| Bundle by area or stop | Small jobs on the same equipment or for the same shutdown | Group so they are planned and done together |
Growing backlog is a symptom
When the backlog grows, the reflex is overtime or a contract crew. That clears it for a while, and it is the right short term answer when the work is ready and the crew is short. If the backlog then grows again, the cause is upstream. A backlog fed by breakdowns and repeat failures is a reliability problem, and the answer is in the maintenance strategy: root cause analysis on the repeat failures, condition based maintenance where failures give warning, and a preventive program that targets the failure modes that matter.
Shrinking backlog is not always good news either. A backlog under about two weeks often means work is not being found: rounds have lapsed, operators have stopped raising notifications because nothing happens to them, or the crew is larger than the work. Operator rounds and a notification process that gives feedback are how the work gets found.
What the CMMS needs
- An estimate of hours on every order, even a rough one, so every order counts.
- The trade, or main trade, on every order.
- A status that says where the order is waiting, kept current.
- Priority set by a rule from consequence and urgency, so old orders can be re-ranked.
- Each trade's weekly capacity, so the report can divide.
- A weekly report of total and ready backlog in crew-weeks by trade, with the trend.
Common questions
What is maintenance backlog?
Maintenance backlog is the work that has been identified and approved but not yet completed: corrective work orders, outstanding preventive work, inspection findings and small projects. It is usually measured in crew-weeks, the estimated labour hours of the open work divided by the hours the crew has available each week, so it says how many weeks the crew would need to clear it if no new work arrived.
How do you calculate maintenance backlog?
Add the estimated remaining labour hours of every open work order for a trade, then divide by that trade's available hours a week. Twelve fitters at 38 hours give 456 hours a week, so 2,280 hours of open mechanical work is 5.0 crew-weeks. Do the same for the work that is ready to schedule, and for each trade separately, since one trade's backlog cannot be worked by another.
What is a healthy maintenance backlog?
A total backlog of roughly two to six crew-weeks is commonly cited, with enough ready work to fill two to three weeks of the schedule. Below about two weeks the crew may run out of planned work, or work is not being identified. Above about six, work is arriving faster than the crew can do it, or the backlog holds work that should have been cancelled. The direction of the trend is more telling than any one week.
What is the difference between total backlog and ready backlog?
Total backlog is all identified work not yet done. Ready backlog is the part of it that could be scheduled tomorrow: planned with a job pack, parts in the store, permits and access known. The scheduler can only draw on ready backlog, so a large total backlog with little ready work means the bottleneck is planning or supply rather than the crew.
How do you reduce a maintenance backlog?
First clean it: close duplicates, cancel work that is no longer needed with a reason, and check priorities and estimates, which often removes a large share. Then find why it grew. If work is arriving faster than planning, add planning capacity. If ready work is piling up, the crew is short and a contract crew or overtime clears it for a time. If corrective work keeps arriving, the fix is in the maintenance strategy, not the crew.
Key terms
Plain-language definitions from our glossary for the concepts this article leans on.
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